function s1_goto_dir() {
    cd "$1"
}
function s2_touch_empty_file_with_given_name() {
    touch "$1"
}
function s3_make_directories() {
    mkdir -p projects/git backup
    cd projects
}
function s4_create_6_files() {
    touch linux1_centos linux1_redhat linux1_c_programming linux2_centos linux2_redhat linux2_c_programming
}
function s5_make_directories_in_git() {
    cd git
    mkdir linux1 linux2
    cd ../..
}
function s6_move_files_to_dir_1_or_2() {
    mv linux1_* git/linux1/
    mv linux2_* git/linux2/
}
function s7_create_package_and_compress() {
    tar -czvf backup/git.tar.gz git
}
function s8_delete_dir_git() {
    rm -rf git
}
function s9_recover_from_git_tar_gz_backup() {
    tar -zxvf backup/git.tar.gz
}
function s10_create_package_and_compress() {
    tar -jcvf backup/git.tar.bz2 git
}
function s11_find_and_sort_alphabetically_all_created_files_and_dirs() {
    find projects -type f,d | sort
}
function s12_get_next_15_minutes_boundary() {
    current_time=$(date '+%Y-%m-%d_%H:%M:%S')
    next_quarter=$(( ( $(date +%M) + 15 ) / 15 * 15 ))
    if [ $next_quarter -gt 59 ]; then
        next_quarter=0
        next_hour=$(( $(date +%H) + 1 ))
    else
        next_hour=$(date +%H)
    fi
    future_time="${current_time:0:11}${next_hour}:00:00"
    echo $future_time
}